Power transformer reinforcing rib structure rigidity maximization optimization method and related device

Abstract

The invention belongs to the technical field of power transformer non-electric quantity protection, and discloses a power transformer reinforcing rib structure rigidity maximization optimization method and related device.The optimization method comprises the steps that geometric models of an oil-immersed power transformer and a reinforcing rib structure are established, and finite element models are loaded; carrying out simulation calculation on an internal arc fault of the oil-immersed power transformer to obtain a fault oil pressure load; carrying out rigidity analysis to obtain a control equation of the transformer box body structure; taking a control equation of the transformer box body structure and a volume constraint equation of the reinforcing rib as constraint conditions, taking rigidity maximization as an optimization objective function, obtaining a design speed of a free boundary shape of the reinforcing rib, updating the shape of the transformer reinforcing rib, and determining an optimal shape of the reinforcing rib structure with maximized rigidity according to an updating result. According to the method, through simulation calculation and sensitivity analysis, the scientificity and efficiency of optimization are improved, and the explosion-proof performance of the oil-immersed power transformer under the internal arc fault condition is effectively enhanced.

Description

Technical Field

[0001] The present invention belongs to the technical field of non - electrical protection of power transformers, and particularly relates to an optimization method for maximizing the structural stiffness of the stiffeners of a power transformer and related devices. Background Art

[0002] As one of the most critical devices in the power system, the reliability and stability of extra - high - voltage large - oil - immersed power transformers directly affect the safe and stable operation of the power grid. When an arc fault occurs inside a large transformer, the surrounding insulating oil quickly vaporizes and decomposes to form high - temperature and high - pressure bubbles. The compression of the surrounding insulating oil by the bubbles correspondingly causes the internal oil pressure of the large transformer to rise. This process poses a great threat to the mechanical structure of the large transformer. If the pressure generated within a short time exceeds the bearing capacity of the oil tank, an explosion accident will occur. In recent years, there have been multiple equipment explosion and combustion accidents caused by high - energy arc faults inside extra - high - voltage large transformers, resulting in serious economic losses and adverse social impacts.

[0003] Currently, the method of welding stiffeners on the outer wall of the transformer oil tank is generally adopted to improve the structural strength of the transformer oil tank and reduce the probability of explosion and combustion accidents. However, at present, the layout and installation dimensions of the stiffeners on the wall of the oil - immersed power transformer are mostly based on trial - and - error iterative design. This requires researchers to have rich engineering experience and may also result in the obtained design scheme not being globally optimal, leading to low safety. Summary of the Invention

[0004] To overcome the problems of unreasonable layout of the stiffeners on the transformer tank wall and low safety existing in the prior art, the purpose of the present invention is to provide an optimization method for maximizing the structural stiffness of the stiffeners of a power transformer and related devices. This method can achieve the maximum - stiffness design under the constraints of the transformer box structure and the volume of the stiffeners, improve the safety of the transformer, and at the same time provide scientific guidance for the design of the oil - immersed power transformer oil tank structure.

[0005] To achieve the above - mentioned purpose, the technical scheme adopted by the present invention is as follows: An optimization method for maximizing the structural stiffness of the stiffeners of a power transformer, comprising the following steps: Establish a geometric model of the oil - immersed power transformer and the stiffener structure, load the finite - element model, and perform simulation calculations on the internal arc fault of the oil - immersed power transformer according to the finite - element model to obtain the fault oil - pressure load; Based on the fault oil - pressure load, perform stiffness analysis on the oil - immersed power transformer and the stiffener structure to obtain the control equation of the transformer box structure; perform analysis on the stiffener structure to obtain the volume constraint equation of the stiffeners; Taking the control equation of the transformer box structure and the volume constraint equation of the stiffeners as constraint conditions and the maximum stiffness as the optimization objective function, obtain the shape gradient function; According to the calculation of the shape gradient function, the design speed of the free boundary shape of the rib is obtained; The shape of the transformer rib is updated using the design speed of the free boundary shape of the rib, and the optimal shape that maximizes the structural stiffness of the rib is determined according to the update result.

[0006] Further, the calculation formula for the fault oil pressure load is:

[0007] In the formula, is the radius of the bubble, is the bubble expansion speed, is the bubble expansion acceleration; is the internal pressure of the bubble, is the insulating oil pressure, is the boundary of the insulating oil domain, is the fluid density, represents the fault oil pressure load.

[0008] Further, the control equation of the transformer box structure is:

[0009] In the formula, represents the bilinear form of the stiffness operator, represents the linear form of the load operator, represents the translational displacement component of the transformer box structure, represents the rotational component about the axis of the transformer box structure, represents the local rotational component of the transformer box structure; represents the translational displacement component of the transformer box structure in the virtual displacement, represents the rotational component about the axis of the transformer box structure in the virtual displacement, represents the local rotational component of the transformer box structure in the virtual displacement, represents the allowable displacement space, means that the equation holds for all virtual displacement fields belonging to the allowable displacement space of.

[0010] Further, the volume constraint equation of the rib is:

[0011] Among them, represents the total volume of the rib, represents the volume constraint value of the rib, represents the rib j volume of the represents thej The area domain of one unit h Denotes the thickness of the stiffener N Denotes the total number of finite elements after the stiffener is discretized, d A Denotes the area microelement

[0012] Furthermore, the shape gradient function Is calculated by the following formula (10) Where Denotes the elastic tensor of the bending stress Denotes the gradient of the actual local rotation field Denotes the gradient of the actual local rotation field equivalent to the virtual local rotation field Denotes the elastic tensor of the membrane stress Denotes the gradient of the actual displacement field Denotes the gradient of the actual displacement field equivalent to the virtual local rotation field Denotes the shear stiffness coefficient Denotes the elastic tensor of the shear stress Denotes the component of the actual local rotation field Denotes the component of the actual rotation field about the axis Denotes the component of the actual local rotation field equivalent to the virtual local rotation field Denotes the component of the actual rotation field about the axis equivalent to the virtual rotation field about the axis Denotes the Lagrange multiplier of the volume constraint equation of the stiffener

[0013] Furthermore, the design velocity of the free boundary shape of the stiffener is calculated by the following formula

[0014] Where Is the in-plane unit outer normal vector on the boundary The design velocity of the free boundary shape of the stiffener Denotes the design velocity of the free boundary shape of the stiffener Is opposite to the direction of the shape gradient function

[0015] Furthermore, the shape of the transformer stiffener is updated using the design velocity of the free boundary shape of the stiffener, and the optimal shape that maximizes the structural stiffness of the stiffener is determined according to the update result, including the following steps ​After updating the shape of the transformer stiffeners using the design speed of the free boundary shape of the stiffeners, a geometric model of the oil-immersed power transformer and the stiffener structure is established, and the loop is performed until the shape of the transformer stiffeners meets the convergence condition. The shape of the transformer stiffeners that meets the convergence condition is taken as the optimal shape for maximizing the stiffness of the stiffener structure.

[0016] In the second aspect of the present invention, there is provided an optimization system for maximizing the stiffness of a power transformer stiffener structure, including: An arc fault simulation calculation module for establishing a geometric model of the oil-immersed power transformer and the stiffener structure, loading a finite element model, and performing an internal arc fault simulation calculation of the oil-immersed power transformer according to the finite element model to obtain a fault oil pressure load; A control equation and volume constraint equation acquisition module for performing a stiffness analysis on the oil-immersed power transformer and the stiffener structure based on the fault oil pressure load to obtain a control equation of the transformer tank structure; analyzing the stiffener structure to obtain a volume constraint equation of the stiffeners; A shape gradient function acquisition module for taking the control equation of the transformer tank structure and the volume constraint equation of the stiffeners as constraint conditions and maximizing the stiffness as an optimization objective function to obtain a shape gradient function; A design speed acquisition module for the free boundary shape of the stiffeners for calculating according to the shape gradient function to obtain the design speed of the free boundary shape of the stiffeners; An update module for updating the shape of the transformer stiffeners using the design speed of the free boundary shape of the stiffeners and determining the optimal shape for maximizing the stiffness of the stiffener structure according to the update result.

[0017] In the third aspect of the present invention, there is provided an electronic device including a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, the optimization method for maximizing the stiffness of the power transformer stiffener structure is implemented.

[0018] In the fourth aspect of the present invention, there is provided a computer-readable storage medium storing a computer program, and when the computer program is executed by a processor, the optimization method for maximizing the stiffness of the power transformer stiffener structure is implemented.

[0019] Compared with the prior art, the beneficial effects of the present invention are as follows: In the present invention, by establishing a geometric model of an oil-immersed power transformer and a stiffener structure, loading a finite element model, and performing simulation calculations to obtain a fault oil pressure load, the mechanical response of the tank wall structure of the oil-immersed power transformer and its stiffeners under internal arc fault conditions can be evaluated. Under the constraints of the control equation of the transformer tank structure and the volume constraint equation of the stiffeners, the stiffness of the stiffener structure of the oil-immersed power transformer is maximized. The present invention overcomes the limitations of the traditional trial-and-error iterative design method based on engineering experience, combines the finite element calculation method with the sensitivity analysis technology, directly obtains the shape gradient function according to the optimization problem of maximizing the stiffness of the stiffeners, avoids the cumbersome calculation process of the stiffness matrix derivative in the traditional method, meets the rapid iterative requirements for the optimization of the stiffener structure of the oil-immersed power transformer tank, and the explosion-proof design requirements under harsh fault conditions. The present invention provides important technical support for the structural safety design of oil-immersed power transformers under fault conditions and has wide practical application value. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a geometric model diagram of the oil-immersed power transformer in the present invention; Figure 2 It is a mesh division diagram of the oil-immersed power transformer in the present invention; Figure 3 It is a flow chart of the method for maximizing the stiffness of the stiffener structure of the oil-immersed power transformer in the present invention; Figure 4 It is an optimized geometric model diagram of the oil-immersed power transformer in the present invention; Figure 5 It is a top cover deformation diagram of the oil-immersed power transformer with an unoptimized stiffener structure in the present invention; Figure 6 It is a top cover deformation diagram of the oil-immersed power transformer after optimizing the stiffener structure in the present invention; Figure 7 It is a schematic diagram of the system for maximizing the stiffness of the stiffener structure of the oil-immersed power transformer in the present invention; In the figure, 1 is the conservator of the power transformer, 2 is the tank of the power transformer, and 3 is the stiffener. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0021] The present invention will be described in detail below with reference to the accompanying drawings.

[0022] The method for maximizing the stiffness of the stiffener structure of the power transformer of the present invention can quickly iteratively update and optimize the boundary shape of the stiffener 3 of the transformer, and achieve the maximization of the stiffness of adding the stiffener 3 structure on the power transformer under the constraints of the control equation of the transformer tank structure and the volume equation of the stiffener.

[0023] See Figure 3, The optimization method for maximizing the structural stiffness of the reinforcing ribs of the power transformer of the present invention includes the following steps: Step (1): Refer to Figure 1 , There is a conservator 1 and reinforcing ribs 3 on the oil tank 2 of the power transformer. The physical model is reasonably simplified to reduce the computational amount of the geometric model while meeting the simulation accuracy.

[0024] Simplify the structure of the oil-immersed power transformer and the reinforcing ribs 3, and then establish a geometric model of the simplified oil-immersed power transformer and the reinforcing ribs 3 structure through Spacecliam software (a three-dimensional solid direct modeling software).

[0025] Step (2): On the geometric model of the oil-immersed power transformer and the reinforcing ribs 3 structure, use ANSYS (Analysis of Systems) software to load the finite element model of the oil-immersed power transformer and the reinforcing ribs 3 structure. For the mesh division situation in the finite element model, refer to Figure 2 , Check the element quality of the mesh model in the finite element model to ensure that the mesh quality in the subsequent optimization process meets the calculation accuracy requirements.

[0026] Step (3): Use the finite element model of the oil-immersed power transformer and the reinforcing ribs 3 structure to conduct a simulation calculation of the internal arc fault of the oil-immersed power transformer, and obtain the fault oil pressure load of the transformer oil tank wall structure and the reinforcing ribs 3. The fault oil pressure load is determined by the volume change of the arc-induced bubbles. The calculation formula for the fault oil pressure load is: (1) In the formula, R is the radius of the bubble, is the bubble expansion speed, is the bubble expansion acceleration; is the internal pressure of the bubble, is the insulating oil pressure, is the insulating oil domain boundary, is the fluid density, characterizes the fault oil pressure load.

[0027] Step (4): Define the regional variables of the oil-immersed power transformer and the reinforcing ribs 3 structure, and define the forces acting on different regions of the oil-immersed power transformer and the reinforcing ribs 3 structure; specifically, the out-of-plane load per unit area on the oil tank of the oil-immersed power transformer is q , the in-plane load per unit area on the oil tank of the oil-immersed power transformer is , represents the component of the in-plane load on the power transformer oil tank along different directions, represents different directions of the load, α When it represents the first direction in the two-dimensional plane of the local coordinate system of the housing (i.e., direction), When it represents the second direction in the two-dimensional plane of the local coordinate system of the housing (i.e., direction), the shear force per unit length caused by the local shear deformation of the fuel tank wall is Q , and the out-of-plane bending moment per unit area at the connection between the stiffener and the fuel tank wall is is the component of the out-of-plane bending moment per unit area at the connection between the stiffener and the fuel tank wall in different directions, and the bending moment per unit length of the stiffener is , is the component of the bending moment per unit length of the stiffener in different directions, and the in-plane load per unit length of the stiffener is , is the component of the in-plane load per unit length of the stiffener in different directions.

[0028] Step (5): According to the fault oil pressure load of the transformer fuel tank wall structure and the stiffener 3, perform a stiffness analysis on the oil-immersed power transformer and the stiffener 3 structure. The control equation of the transformer box structure can be written as: (2) In the formula, represents the bilinear form of the stiffness operator, represents the linear form of the load operator, u 0 represents the translational displacement component of the transformer box structure, which is used to describe the overall translational deformation of the transformer fuel tank and the stiffener 3, represents the rotational component about the axis of the transformer box structure, which is used to describe the bending or torsional deformation of the transformer fuel tank and the stiffener 3, represents the local rotational component of the transformer box structure, which is used to supplement the high-order deformation mode of the transformer fuel tank and the stiffener 3; represents the translational displacement component of the transformer box structure in the virtual displacement, represents the rotational component about the axis of the transformer box structure in the virtual displacement, represents the local rotational component of the transformer box structure in the virtual displacement, represents the allowable displacement space, which contains all displacement fields that satisfy the geometric boundary conditions and continuity, represents that the equation holds for all virtual displacement fields belonging to the allowable displacement space .

[0029] The bilinear form of the stiffness operator and the linear form are defined as follows respectively: (3) Among them, The elastic tensor representing the film stress The elastic tensor representing the bending stress The elastic tensor representing the shear stress u 0 The translational displacement components representing the transformer tank structure The rotational components about the axis representing the transformer tank structure The local rotational components representing the transformer tank structure The translational displacement components of the transformer tank structure in the virtual displacement The rotational components about the axis of the transformer tank structure in the virtual displacement The local rotational components of the transformer tank structure in the virtual displacement j Representing the element number Representing the j area domain of the The gradient of the actual displacement field The gradient of the virtual displacement field The gradient of the actual local rotation field The gradient of the virtual local rotation field Representing the shear stiffness coefficient The actual shear strain components The virtual shear strain components The first deformation direction in the actual field The second deformation direction in the actual field The first deformation direction in the virtual displacement field The second deformation direction in the virtual displacement field = 1, 2 When it is 1, it corresponds to the first direction in the two-dimensional plane of the local coordinate system of the shell, that is direction When it is 2, it corresponds to the second direction in the two-dimensional plane of the local coordinate system of the shell, that is direction. When = 1 = 2 = 2 = 1, the film stress term can be expressed as , Represents the displacement in the actual displacement field along direction along direction of the gradient Represents the displacement in the virtual displacement field along direction along direction of the gradient. The bending stress term can be expressed as , Represents the rotation about in the actual local rotation field The gradient of the bending in the direction, represents the virtual local rotation field around the The gradient of the bending in the direction. The shear stress term can be expressed as , represents the actual transverse shear strain along the direction, represents the actual transverse shear strain along the direction, d A represents the area element, N represents the total number of finite elements after the stiffener is discretized.

[0030] (4) where represents the translational displacement component of the transformer tank structure in the virtual displacement, represents the rotational component around the axis of the transformer tank structure in the virtual displacement, represents the local rotational component of the transformer tank structure in the virtual displacement, is the component of the in-plane load on the upper edge of the power transformer oil tank in different directions, is the component of the out-of-plane bending moment per unit area at the connection between the stiffener and the oil tank wall in different directions, is the out-of-plane load per unit area on the oil-immersed power transformer oil tank, represents the component of the in-plane load per unit length of the stiffener in different directions, represents the component of the bending moment per unit length of the stiffener in different directions, represents the shear force per unit length in the virtual displacement field, represents the virtual displacement field in the direction of the translational component, represents the virtual displacement field in the direction of the local rotational component, N represents the total number of finite elements after the stiffener is discretized, represents the j th element's area domain, used to calculate the load contribution inside the element, represents the j th element's boundary, used to calculate the load contribution on the boundary. d A represents the area element, represents the boundary area element.

[0031] Step (6): Taking the control equation of the transformer tank structure in Equation (2) and the volume constraint equation of the stiffener 3 as the constraint conditions, and maximizing the stiffness as the optimization objective function, the optimization problem of maximizing the stiffness of the stiffener 3 of the oil-immersed power transformer can be written as:

[0032] (5) Among them, represents the bilinear form of the stiffness operator, represents the adjoint variable, represents the state variable, u 0 represents the translational displacement component of the transformer tank structure, represents the rotational component about the axis of the transformer tank structure, represents the local rotational component of the transformer tank structure, represents the translational displacement component of the transformer tank structure in the virtual displacement, represents the rotational component about the axis of the transformer tank structure in the virtual displacement, represents the local rotational component of the transformer tank structure in the virtual displacement, U represents the allowable displacement space, which contains all displacement fields that satisfy the geometric boundary conditions and continuity, represents the total volume of the stiffeners, represents the volume constraint value of the stiffeners, represents the j volume of the th unit of the stiffeners, j represents the h area domain of the N th unit, A represents the thickness of the stiffeners, which is usually a constant or varies with position,

[0033] If represents the Lagrange multiplier of the volume constraint equation of the stiffeners, then the Lagrangian function of this optimization problem L can be expressed as:

[0034] (6) Among them, represents the j area domain of the u 0 represents the translational displacement component of the transformer tank structure, represents the rotational component about the axis of the transformer tank structure, represents the local rotational component of the transformer tank structure, represents the translational displacement component of the transformer tank structure in the virtual displacement, represents the rotational component about the axis of the transformer tank structure in the virtual displacement, Represents the local rotational component of the transformer tank structure in the virtual displacement, Is the linear form of the load operator, representing the virtual work contribution of the external load, Is the bilinear form of the stiffness operator, describing the stiffness characteristics of the structure, Represents the total volume of the stiffeners, Represents the volume constraint value of the stiffeners.

[0035] Assume that the sub-boundary where non-zero external forces (bending moment per unit length of the stiffener M , in-plane load per unit length of the stiffener N and shear force per unit length caused by the local shear deformation of the tank wall Q ) act does not change (i.e., the design velocity of the free boundary shape of the stiffener = 0), and the forces acting on the oil-immersed power transformer tank (in-plane load per unit area on the oil-immersed power transformer tank f , out-of-plane bending moment per unit area at the connection of the stiffener 3 and the tank wall , out-of-plane load per unit area on the oil-immersed power transformer tank ) do not change with space and time (i.e., , is the derivative of the in-plane load per unit length with respect to space and time, is the derivative of the out-of-plane bending moment per unit area with respect to space and time, is the derivative of the out-of-plane load per unit area with respect to space and time). Then, using formula (6), the derivative of the Lagrangian function of this optimization problem is derived: (7) where

[0036] (8) where, Represents the translational displacement component of the transformer tank structure, Represents the shape derivative of the translational displacement component of the transformer tank structure, Represents the rotational component about the axis of the transformer tank structure, Represents the shape derivative of the rotational component about the axis of the transformer tank structure, Represents the local rotational component of the transformer tank structure, Represents the shape derivative of the local rotational component of the transformer tank structure, Represents the translational displacement component of the transformer tank structure in the virtual displacement, Represents the shape derivative of the translational displacement component of the transformer tank structure in the virtual displacement, represents the component of the rotational displacement of the transformer tank structure about an axis in the virtual displacement, represents the shape derivative of the component of the rotational displacement of the transformer tank structure about an axis in the virtual displacement, represents the local rotational component of the transformer tank structure in the virtual displacement, represents the shape derivative of the local rotational component of the transformer tank structure in the virtual displacement, represents the shape gradient function, is the boundary unit outer normal vector in the plane, represents the design velocity of the free boundary shape of the stiffener, represents the admissible function space of the design velocity, N represents the total number of finite elements after the stiffener is discretized, represents the elastic tensor of the bending stress, represents the elastic tensor of the membrane stress, represents the elastic tensor of the shear stress, represents the gradient of the actual local rotation field, represents the gradient of the virtual local rotation field, represents the gradient of the actual displacement field, represents the gradient of the virtual displacement field, represents the shear stiffness coefficient, represents the component of the actual local rotation field, represents the component of the actual rotational displacement field about an axis, represents the component of the virtual local rotation field, represents the component of the virtual rotational displacement field about an axis, represents the Lagrange multiplier of the volume constraint equation of the stiffener, represents the boundary area element.

[0038] Furthermore, it can be deduced that when the optimality conditions of the state variable , the adjoint variable and the Lagrange multiplier of the volume constraint equation of the stiffener are satisfied, the derivative of the Lagrangian function can be simplified to: (9) where, represents the shape gradient function, is the boundary unit outer normal vector in the plane, represents the design velocity of the free boundary shape of the stiffener, belonging to the admissible function space of the design velocity, represents the inner product.

[0039] The shape gradient function is obtained by substituting the self - adjoint relationship into Equation (8): (10) where represents the gradient of the actual local rotation field, represents the gradient of the actual local rotation field equivalent to the virtual local rotation field, represents the gradient of the actual displacement field, represents the gradient of the actual displacement field equivalent to the virtual local rotation field, represents the shear stiffness coefficient, represents the component of the actual local rotation field, represents the component of the actual local rotation field equivalent to the virtual local rotation field, represents the component of the actual rotation field about the axis, represents the component of the actual rotation field about the axis equivalent to the virtual rotation field about the axis.

[0040] Step (7): When the condition of maximizing the stiffness of the stiffener 3 is satisfied, the derivative of the Lagrangian function is equal to 0. Therefore, according to the derivative of the Lagrangian function and the shape gradient function, the design velocity of the free - boundary shape of the stiffener 3 is obtained. According to Equation (9), it can be known that the design velocity of the free - boundary shape of the stiffener 3 is proportional to the shape gradient function and can be expressed as: (11) where is the in - plane unit outer normal vector on the boundary , represents the design velocity of the free - boundary shape of the stiffener, is in the opposite direction to the shape gradient function

[0041] The design velocity of the free - boundary shape of the stiffener 3 is divided into the in - plane design velocity and the out - of - plane design velocity . Furthermore, the analysis control equation of the design velocity of the free - boundary shape of the stiffener 3 is: (12) where is the in - plane design velocity, is the in - plane design velocity along the direction, is the in - plane design velocity along the direction, is the out-of-plane design speed, is the bilinear form of the stiffness operator, is the local rotation design speed, represents the translational displacement component of the transformer tank structure in the virtual displacement, represents the rotational component about the axis of the transformer tank structure in the virtual displacement, represents the local rotational component of the transformer tank structure in the virtual displacement, represents the shape gradient function, is the boundary is the in-plane unit outer normal vector on the boundary, represents the boundary, represents the allowable displacement space, and the superscripts in each variable all represent the element number, represents the admissible function space of the design speed.

[0042] In addition, in order to obtain the optimal free boundary shape of the stiffener 3, the entire region of the transformer tank structure is fixed (i.e., the design speed of the entire region of the transformer tank structure V 0 = 0), and it is assumed that there is no change in the out-of-plane direction of the stiffener 3. Therefore, an additional constraint is imposed on the change in the normal direction of the surface of the stiffener 3 (i.e., the out-of-plane design speed = 0).

[0043] Step (8): Use the design speed of the free boundary shape of the stiffener determined in step (7) to iteratively update the shape of the transformer stiffener 3, and continuously repeat steps (1) - (7) until the iterative convergence condition is met (i.e., the increase in the overall stiffness of the stiffener 3 after two consecutive optimizations is less than the preset threshold) or the constraint condition (the volume constraint equation of the stiffener 3) is met, to obtain the optimal shape that maximizes the structural stiffness of the oil-immersed power transformer stiffener 3.

[0044] Step (9): Output the optimal shape that maximizes the structural stiffness of the oil-immersed power transformer stiffener 3 obtained in step (8).

[0045] For the oil-immersed power transformer and its stiffener 3 structure after the optimization of the stiffener 3, see Figure 4 There is an oil conservator 1 and the optimized stiffener 3 on the power transformer oil tank 2 of the power transformer.

[0046] By comparing and analyzing with the initial shape, compare the deformation amounts of the oil-immersed power transformer tank structure under the oil pressure load generated by the same internal arc fault, and verify the improvement effect of the structural stiffness of the optimized oil-immersed power transformer stiffener 3.

[0047] According to the above optimization method, the deformation amounts of the oil-immersed power transformer with and without the optimization of the reinforcing rib 3 under the oil pressure load generated by the same internal arc fault are as Figure 5 and Figure 6 shown. It is set that the total energy released by the arc fault caused by the internal fault of the oil-immersed power transformer before and after optimization is the same, which is 10 MJ. Figure 5 and Figure 6 show the comparison of the deformation degrees of the transformer box body structure before and after the optimization of the reinforcing rib 3. Refer to Figure 5 and Figure 6 , after the size parameters of the reinforcing rib 3 are optimized, the area where the deformation amount of the central area of the oil tank wall exceeds 22 mm is significantly reduced. The calculation results show that this optimization method realizes the maximization of the stiffness of the reinforcing rib 3 structure of the oil-immersed power transformer, enhances the explosion-proof performance of the transformer box body, and significantly reduces the risk of the transformer explosion accident.

[0048] Refer to Figure 7 , another embodiment of the present invention provides an optimization system for maximizing the stiffness of the reinforcing rib structure of a power transformer, including: An arc fault simulation calculation module, which is used to establish a geometric model of the oil-immersed power transformer and the reinforcing rib structure, load the finite element model, and perform simulation calculations on the internal arc fault of the oil-immersed power transformer according to the finite element model to obtain the fault oil pressure load; A control equation and volume constraint equation acquisition module, which is used to perform stiffness analysis on the oil-immersed power transformer and the reinforcing rib structure based on the fault oil pressure load to obtain the control equation of the transformer box body structure; analyze the reinforcing rib structure to obtain the volume constraint equation of the reinforcing rib; A shape gradient function acquisition module, which is used to take the control equation of the transformer box body structure and the volume constraint equation of the reinforcing rib as constraint conditions, and the maximization of stiffness as the optimization objective function to obtain the shape gradient function; A design speed acquisition module for the free boundary shape of the reinforcing rib, which is used to calculate according to the shape gradient function to obtain the design speed of the free boundary shape of the reinforcing rib; An update module, which is used to update the shape of the transformer reinforcing rib by using the design speed of the free boundary shape of the reinforcing rib, and determine the optimal shape for maximizing the stiffness of the reinforcing rib structure according to the update result.

[0049] Another embodiment of the present invention provides an electronic device, including a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, the optimization method for maximizing the stiffness of the reinforcing rib structure of the power transformer is realized.

[0050] Another embodiment of the present invention provides a computer-readable storage medium storing a computer program, and when the computer program is executed by a processor, the method for maximizing the structural stiffness of the reinforcing rib of the power transformer is implemented.

[0051] The present invention establishes a geometric model and a finite element model of an oil-immersed power transformer and the reinforcing rib 3 structure, and numerically simulates and evaluates the mechanical response of the transformer tank wall structure and its reinforcing rib 3 under internal arc fault conditions. Then, based on the shape gradient function, a sensitivity analysis of the optimization objective is performed on the boundary shape of the reinforcing rib 3. Combining the sensitivity analysis results, the boundary shape of the reinforcing rib 3 is iteratively updated and optimized. Finally, on the premise of meeting the iterative convergence conditions, under the constraints of the control equation of the transformer box body structure and the volume constraint equation of the reinforcing rib, the structural stiffness of the reinforcing rib 3 is maximized, overcoming the limitations of the traditional trial-and-error iterative design method based on engineering experience, combining the finite element calculation method and the sensitivity analysis technology, adapting to the rapid iterative requirements of the structural optimization of the reinforcing rib 3 of the power transformer oil tank 2, and the explosion-proof design requirements under harsh fault conditions. The present invention improves the mechanical compressive capacity and structural safety of the oil-immersed power transformer under internal arc faults.

[0052] Those skilled in the art should understand that the embodiments of the present invention can be provided as a method, a system, or a computer program product. Therefore, the present invention can take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware aspects. Moreover, the present invention can take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, optical storage, etc.) containing computer-usable program code.

[0053] The present invention is described with reference to the flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowchart and / or block diagram, and the combination of processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to the processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing devices to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing devices generate for implementing in the process Figure 1 a process or multiple processes and / or blocks Figure 1 a block or multiple blocks the device for the specified function.

[0054] These computer program instructions can also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to operate in a particular manner, such that the instructions stored in the computer-readable memory produce a manufacture including an instruction device that implements the functions specified in the process Figure 1 one process or multiple processes and / or blocks Figure 1 the functions specified in one block or multiple blocks.

[0055] These computer program instructions can also be loaded onto a computer or other programmable data processing apparatus, such that a series of operational steps are performed on the computer or other programmable apparatus to produce a computer-implemented process, whereby the instructions executed on the computer or other programmable apparatus provide steps for implementing the functions specified in the process Figure 1 one process or multiple processes and / or blocks Figure 1 the functions specified in one block or multiple blocks.

[0056] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them. Although the present invention has been described in detail with reference to the above embodiments, those of ordinary skill in the art should understand that: the specific implementation manners of the present invention can still be modified or equivalently replaced, and any modification or equivalent replacement that does not depart from the spirit and scope of the present invention shall be covered by the protection scope of the present invention.

Claims

1. A method for maximizing the structural stiffness of a power transformer reinforcement, characterized in that: The following steps are involved: Establishing a geometric model of the oil-immersed power transformer and the reinforcing rib (3) structure, and loading a finite element model, performing an internal arc fault simulation calculation of the oil-immersed power transformer based on the finite element model, and obtaining a fault oil pressure load; Based on the fault oil pressure load, the stiffness analysis of the oil-immersed power transformer and the reinforcing rib (3) structure is carried out to obtain the control equation of the transformer box structure; The structure of the reinforcing rib (3) is analyzed to obtain the volume constraint equation of the reinforcing rib (3); Taking the control equation of the transformer box structure and the volume constraint equation of the stiffener (3) as constraint conditions, maximizing the stiffness is taken as the optimization objective function, and the shape gradient function is obtained; The design speed of the free boundary shape of the stiffener (3) is calculated according to the shape gradient function; The shape of the transformer reinforcement rib (3) is updated using the design speed of the free boundary shape of the reinforcement rib (3), and the optimal shape for maximizing the structural stiffness of the reinforcement rib (3) is determined based on the updated result.

2. The method for maximizing the structural stiffness of a power transformer reinforcement according to claim 1, characterized in that: The calculation formula of the fault oil pressure load is: In the formula, is the radius of the bubble, is the bubble expansion speed, is the bubble expansion acceleration; is the pressure inside the bubble, is the insulating oil pressure, is the insulating oil domain boundary, is the fluid density, Indicates fault oil pressure load.

3. The method for maximizing the structural stiffness optimization of a power transformer reinforcement according to claim 1, characterized in that: The control equation of the transformer box structure is: In the formula, represents the bilinear form of the stiffness operator, represents the linear form of the load operator, represents the translational displacement component of the transformer tank structure, represents the axial rotation component of the transformer tank structure, Represents the local rotation component of the transformer tank structure; represents the translational displacement component of the transformer box structure in the virtual displacement, represents the rotational component of the transformer tank structure in the virtual displacement, represents the local rotation component of the transformer tank structure in the virtual displacement, represents the allowable displacement space, Denotes the equation for all spaces that allow displacements The virtual displacement field is established.

4. The method for maximizing the structural stiffness of a power transformer reinforcement according to claim 1, characterized in that: The volume constraint equation of the reinforcing rib (3) is: in, represents the total volume of the reinforcement, represents the volume constraint value of the stiffener, Reinforcement j The volume of a unit, Indicates j The area of ​​the unit, h represents the thickness of the reinforcement rib, N represents the total number of finite elements after the reinforcement is discretized, d A Represents a microelement of area.

5. The method for maximizing the structural stiffness of a power transformer reinforcement according to claim 1, characterized in that: The shape gradient function Calculated by the following formula: (10) in, The elastic tensor representing the bending stress, represents the gradient of the actual local rotation field, represents the gradient of the actual local rotation field equivalent to the virtual local rotation field, The elastic tensor representing the membrane stress, represents the gradient of the actual displacement field, represents the gradient of the actual displacement field equivalent to the imaginary local rotation field, represents the shear stiffness coefficient, The elastic tensor representing the shear stress, represents the component of the actual local rotation field, represents the component of the actual rotation field around the axis, represents the component of the actual local rotation field equivalent to the imaginary local rotation field, represents the component of the actual rotating field equivalent to the virtual rotating field, Lagrange multiplier representing the volume constraint equation for the stiffener.

6. The method for maximizing the structural stiffness optimization of a power transformer reinforcement according to claim 5, characterized in that: The design speed of the free boundary shape of the stiffener (3) is calculated by the following formula: in, For the border The unit external normal vector in the plane on , Design speed representing the free boundary shape of the stiffener With shape gradient function in the opposite direction.

7. The method for maximizing the structural stiffness of a power transformer reinforcement according to claim 1, characterized in that: The shape of the transformer reinforcement rib (3) is updated using the design speed of the free boundary shape of the reinforcement rib (3), and the optimal shape of the reinforcement rib (3) that maximizes the structural stiffness is determined based on the update result, including the following steps: After updating the shape of the transformer reinforcement rib (3) using the design speed of the free boundary shape of the reinforcement rib (3), a geometric model of the oil-immersed power transformer and the reinforcement rib (3) structure is established, and a cycle is performed until the shape of the transformer reinforcement rib (3) meets the convergence condition. The shape of the transformer reinforcement rib (3) that meets the convergence condition is used as the optimal shape for maximizing the structural stiffness of the reinforcement rib (3).

8. A system for maximizing the structural stiffness of a power transformer reinforcement, characterized in that: include: The arc fault simulation calculation module is used to establish a geometric model of the oil-immersed power transformer and the reinforcing rib (3) structure, load a finite element model, perform an arc fault simulation calculation inside the oil-immersed power transformer based on the finite element model, and obtain a fault oil pressure load; A control equation and volume constraint equation acquisition module is used to perform stiffness analysis on the oil-immersed power transformer and the reinforcing rib (3) structure based on the fault oil pressure load, and obtain the control equation of the transformer box structure; The structure of the reinforcing rib (3) is analyzed to obtain the volume constraint equation of the reinforcing rib (3); A shape gradient function acquisition module is used to obtain a shape gradient function by taking the control equation of the transformer box structure and the volume constraint equation of the stiffener (3) as constraint conditions and maximizing the stiffness as the optimization objective function; A design speed acquisition module for the free boundary shape of the reinforcing rib (3), used to calculate the design speed of the free boundary shape of the reinforcing rib (3) according to the shape gradient function; An updating module is used to update the shape of the transformer reinforcement rib (3) using the design speed of the free boundary shape of the reinforcement rib (3), and determine the optimal shape of the reinforcement rib (3) that maximizes the structural stiffness according to the updating result.

9. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that: When the processor executes the computer program, the method for maximizing the structural stiffness optimization of the power transformer reinforcement as described in any one of claims 1 to 7 is implemented.

10. A computer-readable storage medium storing a computer program, characterized in that: When the computer program is executed by a processor, the method for maximizing the structural stiffness optimization of a power transformer reinforcement rib as claimed in any one of claims 1 to 7 is implemented.

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